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1 Table 27.1. 2 Fig. 27.2 X X SpermEgg XX = female XY = male Y X Copyright © McGraw-Hill Education. Permission required for reproduction or display.

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Presentation on theme: "1 Table 27.1. 2 Fig. 27.2 X X SpermEgg XX = female XY = male Y X Copyright © McGraw-Hill Education. Permission required for reproduction or display."— Presentation transcript:

1 1 Table 27.1

2 2 Fig X X SpermEgg XX = female XY = male Y X Copyright © McGraw-Hill Education. Permission required for reproduction or display.

3 3 Fig Copyright © McGraw-Hill Education. Permission required for reproduction or display. Mesonephros Gonadal ridge Kidney Mesonephric duct Paramesonephric (müllerian) duct Cloaca 5- to 6-week embryo; sexually indifferent stage FemaleMale Testes Efferent ductules Epididymis Mesonephric duct forming the ductus deferens Urinary bladder Seminal vesicle Urogenital sinus forming the urethra 7 to 8 weeks Urinary bladder Seminal vesicle Prostate gland Ductus deferens Epididymis Testis Urethra Penis At birth Vestibule Hymen Urethra Vagina Urinary bladder (moved aside) Uterus Ovary Uterine tube Urogenital sinus forming the urethra and lower vagina Urinary bladder (moved aside) Fused paramesonephric ducts forming the uterus Mesonephric duct (degenerating) Paramesonephric duct forming the uterine tube Ovaries 8 to 9 weeks Bulbourethal gland Paramesonephric duct (degenerating)

4 4 Fig Copyright © McGraw-Hill Education. Permission required for reproduction or display. Genital tubercle Urogenital fold Labioscrotal fold Tail 6 weeks 8 weeks Male Phallus: Developing glans of penis Urethral groove Anus Urethral orifice Glans of penis Prepuce Scrotum Perineal raphe Anus Female Developing glans of clitoris Labia minora Urethral groove Labia majora Anus Prepuce Glans of clitoris Urethral orifice Vaginal orifice Perineal raphe Anus 12 weeks 10 weeks

5 5 Copyright © McGraw-Hill Education. Permission required for reproduction or display. 3-month fetus8-month fetus1-month-old infant Parietal peritoneum Epididymis Testis Ductus deferens Pubic symphysis Vaginal process Gubernaculum Scrotal swelling Penis Vaginal process Muscular wall of abdomen Inguinal canal Closed proximal portion of vaginal process Spermatic cord Tunica vaginalis Scrotum Gubernaculum Fig. 27.5

6 6 Fig Copyright © McGraw-Hill Education. Permission required for reproduction or display. Location of pubic symphysis Perineal raphe Urogenital triangle Anal triangle Location of coccyx Anus Location of ischial tuberosity

7 7 Fig Copyright © McGraw-Hill Education. Permission required for reproduction or display. External inguinal ring Spermatic cord: Cremaster muscle Testicular artery Ductus deferens Pampiniform plexus Epididymis Tunica vaginalis Testis Fascia of spermatic cord Superficial fascia of penis Deep fascia of penis Prepuce (foreskin) Glans Median septum of scrotum Cremaster muscle Dartos muscle Scrotal skin

8 8 Fig Copyright © McGraw-Hill Education. Permission required for reproduction or display. Pelvic cavity Testicular artery 37°C Blood flow Arterial blood cools as it descends 35°C Testis Pampiniform plexus Blood flow Heat transfer Venous blood carries away heat as it ascends Coolest blood Warmest blood Key

9 9 Ductus deferens Head of epididymis Testis, covered by tunica albuginea Tail of epididymis Scrotum (folded down) Interstitial cells Blood vessel Germ cells Sustentacular cell Tails of spermatozoa (a) 2 cm Head of epididymis Ductus deferens Efferent ductule Body of epididymis Spermatic cord Blood vessels and nerves Seminiferous tubule Septum Lobule Tunica vaginalis Tunica albuginea Tail of epididymis Blood vessel Seminiferous tubule Spermatids Sustentacular cell nuclei Tubule lumen Germ cells Connective tissue wall of tubule Interstitial cells (c) (d) 50 µm (b) Spermatic cord Rete testis Fig a: ©McGraw-Hill Education/Dennis Strete; c: ©Dr. Kessel & Dr. Kardon/Tissues and Organs/Visuals Unlimited, Inc.; d: ©Ed Reschke Copyright © McGraw-Hill Education. Permission required for reproduction or display.

10 10 Fig Urinary bladder Pubic symphysis Root of penis Ductus (vas) deferens Shaft of penis Corpus cavernosum Corpus spongiosum Epididymis Glans of penis Prepuce Testis Scrotum Rectum Ampulla of ductus deferens Seminal vesicle Ejaculatory duct Prostate gland Bulbourethral gland Bulbospongiosus muscle Urethra Ureter (a) Sagittal section Urinary bladder Prostate gland Prostatic urethra Membranous urethra Ductus deferens Ampulla Seminal vesicle Ejaculatory duct Bulbourethral gland Bulb Crus Corpus spongiosum Corpus cavernosum Testis Efferent ductules Epididymis Spongy (penile) urethra Glans of penis (b) Posterior view Penis Copyright © McGraw-Hill Education. Permission required for reproduction or display.

11 11 Fig Copyright © McGraw-Hill Education. Permission required for reproduction or display. Dorsal vein Dorsal artery Dorsal nerve Dorsal Corpus spongiosum Corpus cavernosum Deep fascia Superficial fascia Skin Urethra Deep artery Tunica albuginea Lacunae Median septum Corpus spongiosum Prepuce Ventral (b) Glans of penis External urethral orifice (a)

12 12 Fig GnRH from hypothalamus stimulates the anterior pituitary to secrete FSH and LH. 2 FSH stimulates sustentacular cells to secrete androgen-binding protein (ABP). 3 LH stimulates interstitial cells to secrete testosterone (androgen). 4 In the presence of ABP, testosterone stimulates spermatogenesis. Hypothalamus Libido InhibinFSH LH Secondary sex organs Secondary sex characteristics GnRH Pituitary gland Testis Sustentacular cells ABP Interstitial cells 1 Testosterone also stimulates the libido and the development of secondary sex organs and characteristics. Testosterone has negative feedback effects that reduce GnRH secretion and pituitary sensitivity to GnRH Sustentacular cells also secrete inhibin, which selectively inhibits FSH secretion and thus reduces sperm production without reducing testosterone secretion Inhibition Stimulation Key Testosterone Spermatogenesis Copyright © McGraw-Hill Education. Permission required for reproduction or display.

13 13 Meiosis I (first division)Meiosis II (second division) Early prophase I Chromatin condenses to form visible chromosomes; each chromosome has 2 chromatids joined by a centromere. Mid- to late prophase I Homologous chromosomes form pairs called tetrads. Chromatids often break and exchange segments (crossing-over). Centrioles produce spindle fibers. Nuclear envelope disintegrates. Metaphase I Tetrads align on equatorial plane of cell with centromeres attached to spindle fibers. Anaphase I Homologous chromosomes separate and migrate to opposite poles of the cell. Telophase I New nuclear envelopes form around chromosomes; cell undergoes cytoplasmic division (cytokinesis). Each cell is now haploid. Chromosome Nucleus Centromere Centrioles Tetrad Crossing-over Spindle fibers Centromere Chromatid Equatorial plane Cleavage furrow Final product is 4 haploid cells with single-stranded chromosomes. Telophase II New nuclear envelopes form around chromosomes; chromosomes uncoil and become less visible; cytoplasm divides. Anaphase II Centromeres divide; sister chromatids migrate to opposite poles of cell. Each chromatid now constitutes a single-stranded chromosome. Metaphase II Chromosomes align on equatorial plane. Prophase II Nuclear envelopes disintegrate again; chromosomes still consist of 2 chromatids. New spindle forms. Fig Copyright © McGraw-Hill Education. Permission required for reproduction or display.

14 14 Fig Copyright © McGraw-Hill Education. Permission required for reproduction or display. Cross section of seminiferous tubules Lumen of seminiferous tubule Sperm Secondary spermatocyte Blood–testis barrier Primary spermatocyte Sustentacular cell Type B spermatogonium Tight junction Type A spermatogonium Basement membrane of seminiferous tubule Spermiogenesis Meiosis II Meiosis I n n n n n n 2n2n n2n 2n2n Spermatid

15 15 Fig Golgi complex Acrosomal vesicle Nucleus Bridge to adjacent spermatid Acrosome Head Axoneme Mitochondria Midpiece of tail Basal body Flagellum Excess cytoplasm Appearance of acrosomal vesicle and flagellum in spermatid Growth of acrosome and flagellum Shedding of excess cytoplasm Mature sperm Copyright © McGraw-Hill Education. Permission required for reproduction or display.

16 16 Fig Copyright © McGraw-Hill Education. Permission required for reproduction or display. Head Acrosome Nucleus Basal body Mitochondrion Axoneme Midpiece of tail Principal piece of tail Endpiece of tail 2 µm (b)(a) a: ©David Phillips/Visuals Unlimited

17 17 Fig Copyright © McGraw-Hill Education. Permission required for reproduction or display. Excitement Stimulation of genital region, especially glans Visual, mental, and other stimuli Internal pudendal nerve Pelvic nerve Efferent parasympathetic signals Spinal cord (sacral) Spinal cord (L1–L2) Efferent sympathetic signals Deep artery of penis dilates; erectile tissues engorge with blood; penis becomes erect Trabecular muscle of erectile tissues relaxes; allows engorgement of erectile tissues; penis becomes erect Bulbourethral gland secretes bulbourethral fluid Orgasm — emission stage Ductus deferens exhibits peristalsis; sperm are moved into ampulla; ampulla contracts; sperm are moved into urethra Prostate secretes components of the seminal fluid Seminal vesicles secrete components of the seminal fluid Afferent signals Semen in urethra Prostate releases additional secretion Seminal vesicles release additional secretion Efferent sympathetic signals Spinal cord (L1–S4) Efferent somatic signals Bulbocavernosus muscle contracts, and rhythmically compresses bulb and root of penis; semen is expelled (ejaculation occurs) Internal urethral sphincter contracts; urine is retained in bladder Resolution Spinal cord (L1–L2) Efferent sympathetic signals Penis becomes flaccid (detumescent) Trabecular muscles contract; squeeze blood from erectile tissues Internal pudendal artery constricts; reduces blood flow into penis Orgasm — expulsion stage

18 18 Fig Copyright © McGraw-Hill Education. Permission required for reproduction or display. Phosphodiesterase inhibitors Sexual stimulation Nitric oxide Inactive guanylate cyclase GTP Active guanylate cyclase cGMP Vasodilation and erection Loss of erection Degraded by PDE5


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