Male Reproductive System Prof Zheng-Wei Yang / Department of Histology & Embryology / Morphometric Research Laboratory / Tel: 2242778 (O); E-mail: zwyang@nsmc.edu.cn Webpage: http://www.nsmc.edu.cn/forum/stereology/ Bilingual slides of a histology lecture, April 2013 /, 2013 4
Commonly spoken words / Morphological (a. a.) Cell (n. n.) Cellular (a. a.) Nucleus Nuclei Nuclear Tissue Shape Function Develop Divide Section Micrograph Schematic illustration
Commonly spoken sentence patterns / What s s this It s This is Here we see It consists of It s s composed of It contains They re Leydig cells secreting testosterone. They re Leydig cells that secret testosterone. They re Leydig cells, which secret testosterone.
Gender Difference / Appearance after puberty: Secondary sex characteristics Examples? Physiology: Androgens (testosterone ) Genetics: Chromosomes : 46,XY Genes
Peacock s s Display! Are the peacocks male? When? When they court What is it? Borrowed photos /
Primary functions / Sperm / Fertility / Testosterone / Masculinity / Spermatogenesis / Sexual function /
Sperm : - Seen in semen (1667) - Produced by testis (1841) Borrowed photos / Sperm in semen smear Microscope A. van Leeuwenhoek (Dutch, 1632-1723) 1723)
Testosterone : - Secreted by testis (1849) Castration / Implantation of testis Borrowed photos / A. Berthold (German, 1803-1861) 1861)
Testosterone : - Secreted by Leydig cells in the testis (1903) - Synthesized / : in 1935 Nobel prize in chemistry 1939: A. Butenandt (German, 1903-1995), 1995), for f his work on sex hormones Borrowed photos
History of eunuchs castrated men / ( 21 221 ), The earliest records for intentional castration to produce eunuchs are from the Sumerian city of Lagash in the 21st century BC. The human being must have known very well the function of the testis, long long ago
Borrowed photo /
Rabbit /
Borrowed photo / Descent of the Testis Formation of the Tunica Vaginalis
Borrowed photo / Tunica Albuginea - mediastinum testis Seminiferous Tubules / in lobules / tubuli recti rete testis Interstitial Tissue loop
Tunica Albuginea Seminiferous Tubules Straight Tubule Interstitial Tissue Borrowed photo /
The rat rete testis /
The seminiferous tubule / Lumen Seminiferous epithelium Spermatogenic cells Spermatids Spermatocytes Spermatogonia Sertoli cells Basement membrane Myoid cells Borrowed photo /
Spermatids - Adluminal, many - Round to elongated Spermatocytes - Large, many - Mottled appearance Spermatogonia - Scattered on the BM - Round or oval Sertoli cells - Irregular, pale - Single nucleolus Borrowed photo /
Spermatozoa / (Mature spermatids) Head / - Nucleus / - Acrosome / Tail / - Flagellum / ( cilium / ) - Microtubules Mitochondria Borrowed photo
Semen / Plasma : 60% (seminal vesicles), 30% (prostate) Sperm : > 40 10 6 / ml; > 50% motile Smear
Sertoli cells Envelop germ cells Secrete testicular fluid, ABP & inhibin, Tight junctions - Compartments / - Blood-testis barrier Borrowed photo / Foreign cells?
Interstitial tissue Connective tissue Leydig cells - In groups - Large - Lipid - Testosterone The cat testis Borrowed photo /
EM characteristics of steroid-secreting secreting cells: Lipid droplets, ser & Mitochondria Borrowed photo /
Spermatogenesis / Type A spermatogonia Type B spermatogonia Primary spermatocytes (early & later stages) Secondary spermatocytes Spermatids (early round, elongating, late elongated) Spermatozoa
Spermiogenesis Shape changes - Nucleus - Flagellum Golgi complexes Acrosome Residual body Borrowed photo /
Spermiation: release of mature spermatids from Sertoli cells into the tubule lumen Sertoli
Cellular associations Stages Helical in humans or Segmental in others, along the tubule The adult rabbit testis /
The adult human testis /
/ The rat testicular section
Serial optical sections within a rat testicular section --
Hormonal Regulation of Spermatogenesis GnRH from the hypothalamus stimulates adenohypophysis to secrete gonadotrophins LH and FSH. T and FSH maintain spermatogenesis via Sertoli cells. (LH stimulates Leydig cells to secrete T.) High levels of T inhibits LH and FSH. Inhibin secreted by Sertoli cells inhibits FSH.
Seminiferous epithelium in the immature or prepubertal testis: without mature spermatids Borrowed photo /
Epididymis / Head: ductuli efferentes + ductus epididymis Body: ductus epididymis Rabbit Tail: ductus epididymis Borrowed photo /
Epididymal Duct / Pseudostratified epithelium Numerous stereocilia Surrounded by smooth muscle sperm mass
Vas deferens / Mucosa / Muscularis / Fibrosa / V a s e c t o m y Borrowed photo / 1. Will the volume of semen be reduced postvasectomy? 2. Will the man be feminized after vasectomy?
Prostate / 30-50 tubuloalveolar glands / Fibromuscular stroma / * Borrowed photo /
Adenocarcinoma Nodular Hyperplasia Borrowed photos /
Cryptorchidism in rabbits / Normal (Control) Intra-abdominal abdominal (3 months)
Androgen abuse in sports : To enhance muscle mass & strength Will extra testosterone increase libido? Will it promote spermatogenesis?
Normal man T treatment (20 weeks)
Hormonal Male Contraception Extra (supraphysiological levels) T (testosterone) suppressed spermatogenesis? Exogenous T induced withdrawal of FSH and LH, and thus severe suppression of intra-testicular testicular T? FSH LH