Epididymis. Spermatozoa produced in seminiferous tubules are transported to and stored/mature in the epididymis. Vas deferens transports sperm, seminal vesicle contributes fluid.
Leydig cells. Interstitial (Leydig) cells in the testes synthesize testosterone. Sertoli cells support spermatogenesis.
Seminal vesicle. Seminal vesicles produce the major volume of seminal plasma rich in fructose and prostaglandins; prostate and bulbourethral glands add additional secretions.
Penis. The clitoris and penis develop from the same embryonic tissue and are homologous structures.
Uterus. The blastocyst implants into the endometrium (uterine lining); implantation in tube causes ectopic pregnancy.
Allantois. The allantois contributes to formation of the umbilical vessels and connecting stalk of the umbilical cord; chorion and amnion also contribute to fetal membranes.
Prolactin. Prolactin from anterior pituitary stimulates milk synthesis (lactogenesis); oxytocin mediates milk ejection (let-down).
Microlecithal and non-cleidoic. Mammalian ova have very little yolk (microlecithal) and are not enclosed by a shell (non-cleidoic).
Capacitation. Capacitation (in female reproductive tract) renders sperm capable of fertilizing by membrane changes and hyperactivation. Cortical reaction occurs in the oocyte after sperm entry.
Colostrum. The first secretion is colostrum—rich in proteins, antibodies (especially IgA) and immune factors.
IgA. Colostrum contains high levels of secretory IgA which provides passive mucosal immunity to the newborn.
Sertoli cells. Sertoli cells secrete ABP which binds testosterone in the seminiferous tubules, maintaining high local androgen concentration for spermatogenesis.
Luteal phase is characterized by high progesterone (from corpus luteum) and inhibited FSH/LH; a rise in FSH does not occur in the luteal phase. The other matches are correct.
Both statements true. Testes are located in the scrotum outside the abdominal cavity; the scrotum maintains a temperature about 2°C lower than body temperature which is essential for normal spermatogenesis.
A and R are true, R is the correct explanation of A
A is correct. R is not correct as stated: ovulation occurs at mid-cycle (the ovulatory phase) around the end of the follicular/preovulatory period, and is usually described as a separate ovulatory event rather than occurring throughout the follicular phase.
A is true, R is false
Both statements false. The sperm head contains the nucleus and the acrosome. Mitochondria are located in the mid-piece (neck) arranged helically around the flagellum, not in the acrosome.
Both A and R are false
Spermatogenesis: entire process of formation of male gametes from spermatogonia via mitotic divisions and two meiotic divisions producing haploid spermatids (stages: spermatogonia → primary spermatocyte → secondary spermatocyte → spermatid); involves cell proliferation and meiosis. Spermiogenesis: final phase of spermatogenesis; cytodifferentiation of haploid spermatids into spermatozoa — condensation of nucleus, acrosome formation, flagellum formation, mitochondrial aggregation in mid-piece and shedding of excess cytoplasm. Key terms: spermatogonia, meiosis, spermatids, acrosome, flagellum, cytodifferentiation.
Spermatogenesis: entire process of formation of male gametes from spermatogonia via mitotic divisions and two meiotic divisions producing haploid spermatids (stages: spermatogonia → primary spermatocyte → secondary spermatocyte → spermatid); involves cell proliferation and meiosis. Spermiogenesis: final phase of spermatogenesis; cytodifferentiation of haploid spermatids into spermatozoa — condensation of nucleus, acrosome formation, flagellum formation, mitochondrial aggregation in mid-piece and shedding of excess cytoplasm. Key terms: spermatogonia, meiosis, spermatids, acrosome, flagellum, cytodifferentiation.
Male newborn: germ cells are present as spermatogonial stem cells (gonocytes/spermatogonia) — mitotically quiescent until puberty; no mature sperm. Female newborn: oocytes are present as primary oocytes arrested in prophase I (dictyate/diplotene stage) of meiosis I until puberty/ovulation.
Male newborn: germ cells are present as spermatogonial stem cells (gonocytes/spermatogonia) — mitotically quiescent until puberty; no mature sperm. Female newborn: oocytes are present as primary oocytes arrested in prophase I (dictyate/diplotene stage) of meiosis I until puberty/ovulation.
a. FSH — Follicle Stimulating Hormone b. LH — Luteinizing Hormone c. hCG — human Chorionic Gonadotropin d. hPL — human Placental Lactogen
a. FSH — Follicle Stimulating Hormone b. LH — Luteinizing Hormone c. hCG — human Chorionic Gonadotropin d. hPL — human Placental Lactogen
Polyspermy is prevented mainly by the cortical (zona) reaction. After first sperm fusion, cortical granules in the oocyte release enzymes that modify zona pellucida glycoproteins (e.g. alter ZP3 receptors) and harden the zona pellucida (zona reaction), preventing further sperm binding and penetration. Changes in oocyte membrane and other blocks also contribute.
Polyspermy is prevented mainly by the cortical (zona) reaction. After first sperm fusion, cortical granules in the oocyte release enzymes that modify zona pellucida glycoproteins (e.g. alter ZP3 receptors) and harden the zona pellucida (zona reaction), preventing further sperm binding and penetration. Changes in oocyte membrane and other blocks also contribute.
Colostrum: first postpartum secretion of mammary glands. Significance: provides passive immunity to the newborn (high IgA) protecting mucosal surfaces, supplies concentrated proteins and minerals, acts as a mild laxative helping expel meconium, contains growth factors (EGF) and lactoferrin that aid gut maturation and inhibit pathogens, and helps initiate neonatal nutrition and thermoregulation.
Colostrum is the first milk secreted by the mammary glands immediately after childbirth; it is thick, yellowish and rich in antibodies (especially secretory IgA), proteins, vitamins and growth factors.
Justification: trophoblast (syncytiotrophoblast) produces human chorionic gonadotropin (hCG) to maintain corpus luteum early in pregnancy; placenta produces progesterone and estrogens (from maternal and fetal steroid precursors) to maintain endometrium and promote uterine growth; human placental lactogen (hPL) modulates maternal metabolism and mammary gland development; relaxin and peptide hormones influence cervical and pelvic changes. These secretions exert endocrine (systemic) effects on mother and fetus, so the placenta is an endocrine tissue.
The placenta synthesizes and secretes hormones — hCG, progesterone, estrogens, human placental lactogen (hPL) and relaxin — that regulate pregnancy and fetal development, thus functioning as an endocrine organ.
Sketch description (text labels to substitute diagram): - Head: flattened, contains haploid nucleus; anterior acrosome with hydrolytic enzymes (acrosin) for zona penetration. - Neck: contains centrioles; connects head to tail. - Middle piece: cylindrical, packed with spiral mitochondria that supply ATP for motility. - Principal piece (tail): longest flagellar segment with axoneme (9+2 microtubule arrangement) producing propulsion. - End piece: terminal tapering portion of flagellum. Include plasma membrane enveloping the whole cell.
Labels/features of a human spermatozoan: head (acrosome anterior, nucleus), neck (proximal and distal centrioles), middle piece (mitochondrial sheath), principal piece (flagellum), end piece (terminal flagellum), plasma membrane.
Functions: (1) Negative feedback on anterior pituitary to suppress follicle stimulating hormone (FSH) secretion, thereby regulating spermatogenesis and folliculogenesis. (2) In females helps modulate FSH during the menstrual cycle to ensure selection of dominant follicle. (3) Acts locally within gonads to regulate gamete maturation.
Inhibin is a peptide hormone secreted by Sertoli cells (males) and granulosa cells (females) that specifically inhibits FSH secretion from the anterior pituitary.
Importance: cooler scrotal environment permits efficient spermatogenesis and sperm maturation; thermoregulatory muscles (cremaster and dartos) adjust testicular position to regulate temperature. Descent of testes during development places them in scrotum; failure to descend (cryptorchidism) impairs fertility and increases risk of malignancy.
Testes are located in the scrotum outside the abdominal cavity to maintain a temperature ~2–4°C below core body temperature, which is essential for normal spermatogenesis.
Composition details: seminal vesicles contribute ~60–70% of volume (fructose—energy for sperm, prostaglandins, fibrinogen), prostate contributes ~20–30% (alkaline fluid, citric acid, proteolytic enzymes including PSA for liquefaction, zinc), testes contribute spermatozoa (2–5%) and epididymal secretions (maturation factors), bulbourethral glands add mucus for lubrication. Semen pH ~7.2–7.7 to neutralize vaginal acidity. Contains hormones, nutrients and cofactors essential for sperm motility and survival.
Semen = spermatozoa + seminal plasma (fluid from seminal vesicles, prostate and bulbourethral glands). Major components: sperm cells, fructose, prostaglandins, fibrinogen, alkaline fluid, citric acid, enzymes (prostate-specific antigen), zinc, mucus and buffers.
Detailed sequence: 1. Capacitation: sperm undergo biochemical changes in the female reproductive tract to become capable of fertilization (membrane changes, hyperactivation). 2. Transit to ampulla: sperm reach the ampullary region of the oviduct where the secondary oocyte is present. 3. Acrosome reaction: on contact with zona pellucida (ZP), acrosomal enzymes are released to digest ZP glycoproteins (ZP3 mediates binding), allowing one or few sperm to pass. 4. Penetration: sperm traverse corona radiata and zona pellucida to reach oolemma and bind to receptors; membranes fuse and the sperm nucleus enters the oocyte. 5. Cortical reaction: cortical granules in oocyte release contents that modify the zona pellucida to block polyspermy (zona reaction). 6. Completion of oocyte meiosis: the secondary oocyte completes meiosis II producing the ovum and a second polar body. 7. Pronuclear formation and syngamy: male and female pronuclei form, migrate together, and their chromosomes unite to form a diploid zygote. 8. Cleavage and blastocyst formation: zygote divides to form morula then blastocyst (inner cell mass and trophoblast). 9. Hatching: blastocyst breaks free from zona pellucida. 10. Implantation: about 6–7 days post-fertilization the blastocyst adheres to the receptive endometrium; trophoblast differentiates into cytotrophoblast and syncytiotrophoblast, which invades the endometrium. Endometrium undergoes decidual reaction; syncytiotrophoblast contributes to early placentation and secretion of hCG to maintain corpus luteum. This establishes maternal–fetal interface.
Fertilization: capacitation of sperm in female tract, acrosome reaction, penetration of corona radiata and zona pellucida, sperm–oocyte membrane fusion, cortical reaction preventing polyspermy, formation of male and female pronuclei and syngamy. Implantation: cleavage to blastocyst, hatching from zona, adhesion to receptive endometrium, invasion by trophoblast (syncytiotrophoblast) and establishment of early placenta.
Definition expanded: involves proliferation of primordial germ cells to spermatogonia or oogonia, meiotic divisions (reduction division) producing haploid cells, and spermiogenesis or oocyte maturation to produce functional spermatozoa or ova. Includes spermatogenesis in testes and oogenesis in ovaries.
Gametogenesis is the process by which gametes (sperm and ova) are formed from germ cells in the gonads through mitosis, meiosis and differentiation.
Textual labelled description to substitute diagram: - Corona radiata: several layers of follicle cells surrounding the zona; provide nutrients and support. - Zona pellucida: acellular glycoprotein layer (ZP1, ZP2, ZP3) that mediates sperm binding and prevents polyspermy after fertilization. - Oolemma (vitelline membrane): plasma membrane of the oocyte. - Ooplasm: cytoplasm rich in yolk granules, ribosomes, mitochondria, and maternal mRNAs and proteins needed for early development. - Nucleus: haploid oocyte nucleus (germinal vesicle in arrested prophase I or female pronucleus after fertilization). - Cortical granules: just beneath oolemma; release contents during cortical reaction to modify zona pellucida. - Polar body: small cell produced during unequal meiotic divisions, contains discarded chromosomes. (Human ovum diameter ~100–120 µm).
Key structural features/labels of human ovum: corona radiata (outer follicular cells), zona pellucida (glycoprotein layer), oolemma (oocyte plasma membrane), ooplasm (cytoplasm), haploid nucleus (female pronucleus when formed), cortical granules, polar body.
Schematic notes: Spermatogenesis occurs continuously from puberty in seminiferous tubules; involves Sertoli cell support and yields many motile sperm. Oogenesis begins prenatally: primary oocytes arrested in prophase I until puberty; one primary oocyte completes meiosis I monthly producing a large secondary oocyte (arrested at metaphase II) which is ovulated; only on fertilization does meiosis II complete to form a functional ovum; results in one ovum and polar bodies (unequal cytokinesis).
Spermatogenesis: Spermatogonium (2n) → (mitosis) primary spermatocyte (2n) → (meiosis I) two secondary spermatocytes (n) → (meiosis II) four spermatids (n) → (spermiogenesis) four spermatozoa. Oogenesis: Oogonium (2n) → (mitosis) primary oocyte (2n, arrested prophase I) → (meiosis I at ovulation) secondary oocyte (n) + first polar body → (meiosis II at fertilization) ovum (n) + second polar body.
Detailed explanation: 1. Menstrual phase (days 1–4/5): decline of progesterone and estrogen (if no pregnancy) causes spiral artery constriction, necrosis and shedding of functional layer of endometrium — menstrual bleeding. FSH levels begin to rise, stimulating follicular growth. 2. Proliferative (follicular) phase (days 5–14): rising FSH promotes development of ovarian follicles and estradiol (estrogen) secretion by growing follicles. Estrogen stimulates regeneration and proliferation of endometrium (thickening, formation of glands and vascularization). A dominant follicle (Graafian follicle) emerges. High estrogen exerts positive feedback late in the follicular phase, leading to LH surge. 3. Ovulation (around day 14): LH surge triggers rupture of Graafian follicle and release of the secondary oocyte arrested in metaphase II. Estrogen level peaks just before ovulation. 4. Secretory (luteal) phase (days 15–28): after ovulation the ruptured follicle becomes corpus luteum which secretes progesterone (and some estrogen). Progesterone transforms the endometrium into a secretory state: glands become coiled and secrete nutrient-rich fluid, endometrium becomes receptive for implantation. If fertilization does not occur, corpus luteum degenerates to corpus albicans, progesterone and estrogen fall causing menstruation to start again. Hormonal regulation: FSH and LH from anterior pituitary (regulated by GnRH) control ovarian events; estrogen and progesterone exert feedback on pituitary and hypothalamus.
Menstrual cycle phases: menstrual (days 1–5), proliferative/follicular (days 6–14), ovulation (~day 14), secretory/luteal (days 15–28). Each phase corresponds to hormonal changes (FSH, LH, estrogen, progesterone) and endometrial/ovarian events.
Roles in detail: Oxytocin is released in response to cervical stretch and suckling; during labor it increases strength and frequency of uterine contractions (positive feedback loop: stretch → oxytocin → stronger contractions → more stretch). During lactation, oxytocin causes contraction of myoepithelial cells in mammary alveoli and ducts, resulting in milk ejection. Relaxin (placental and ovarian) increases flexibility of the pubic symphysis and cervix by remodeling connective tissue, aiding passage of the fetus through the birth canal and enabling cervical dilation. Relaxin may also modulate uterine contractility and blood flow to the placenta.
Oxytocin: from posterior pituitary stimulates uterine contractions (parturition) via positive feedback and causes milk ejection (let-down) by contracting myoepithelial cells around alveoli. Relaxin: from corpus luteum and placenta softens cervix and relaxes pubic symphysis/ligaments facilitating parturition.
Reconstructed question: "Identify the given image (female reproductive system) and label parts a, b, c and d." Labels and brief functions: a: Ovary — produces ova and ovarian hormones (estrogen, progesterone); b: Fallopian tube/oviduct (ampulla) — site of fertilization and transport of ovum; c: Uterus (body) — site of implantation and fetal development; d: Cervix — lower uterine segment that opens into vagina, acts as barrier and dilates during childbirth. (Note: image was not provided; labels are assigned to the most likely textbook figure.)
Assumed image: human female reproductive tract (schematic). a — Ovary; b — Fallopian tube (oviduct/ampulla); c — Uterus (body); d — Cervix (or vagina opening).
a) Ovulation is shown by the ruptured Graafian follicle releasing the secondary oocyte; stage = secondary oocyte (metaphase II). b) Hormones: Rising estradiol from the follicle causes positive feedback leading to an LH surge from anterior pituitary; LH surge triggers ovulation. c) Simultaneous uterine events: under prior estrogen the endometrium has proliferated; after ovulation progesterone from corpus luteum induces secretory changes — glands enlarge and secrete glycogen-rich fluid, stroma becomes edematous and highly vascular to receive an embryo. d) C vs H (assumption): C (corpus luteum) — endocrine, produces progesterone, supports early pregnancy; H (corpus albicans) — degenerated corpus luteum, connective-tissue scar, no hormone secretion.
a) The figure showing the ruptured mature (Graafian) follicle illustrates ovulation; it represents release of a secondary oocyte arrested in metaphase II. b) Ovarian hormone: estrogen (produced by the mature follicle); Pituitary hormone: LH (luteinizing hormone surge). c) Uterine changes: endometrium moves from proliferative to secretory phase under progesterone (after corpus luteum forms): becomes thicker, more glandular and vascularized; glands secrete nutrient-rich fluid preparing for implantation. d) Difference between C and H (assumed C = corpus luteum; H = corpus albicans): corpus luteum is yellow, functional, secretes progesterone and some estrogen; corpus albicans is a pale fibrous scar (degenerate corpus luteum), non-functional and hormone-inactive.