Spermatid
From Wikipedia, the free encyclopedia
| Spermatid | |
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| Germinal epithelium of the testicle. 1: basal lamina 2: spermatogonia 3: spermatocyte 1st order 4: spermatocyte 2nd order 5: spermatid 6: mature spermatid 7: Sertoli cell 8: tight junction (blood testis barrier) |
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| Transverse section of a tubule of the testis of a rat. X 250. | |
| Gray's | subject #258 1243 |
| MeSH | Spermatids |
The term spermatid refers to the haploid male gametid that results from division of secondary spermatocytes. As a result of meiosis, each spermatid contains only half of the genetic material present in the original primary spermatocyte.
Spermatids are connected together by cytoplasmic material and have superfluous cytoplasmic material around their nuclei.
When formed, early round spermatids must undergo further maturational events in order to develop into spermatozoa, a process termed spermiogenesis (also termed spermeteliosis).
The spermatids begin to grow a tail, develop a thickened mid-piece where the mitochondria become localised and form an acrosome. Spermatid DNA also undergoes packaging, becoming highly condensed. The DNA is packaged firstly with specific nuclear basic proteins, which are subsequently replaced with protamines during spermatid elongation. The resultant tightly packed chromatin is transcriptionally inactive.
[edit] Additional images
 Scheme showing analogies in the process of maturation of the ovum and the development of the spermatids (young spermatozoa). |
[edit] External links
- Histology at BU 17804loa - "Male Reproductive System: testis, early spermatids"
- Histology at BU 17805loa - "Male Reproductive System: testis, late spermatids"
- Histology at okstate.edu
Scrotum : layers (skin, Dartos, External spermatic fascia, Cremaster, Internal spermatic fascia) - Perineal raphe - Spermatic cord
Testes: layers (Tunica vaginalis, Tunica albuginea), Appendix, Mediastinum, Lobules, Septa, Leydig cell, Sertoli cell, Blood-testis barrier
Spermatogenesis: Spermatogonium, Spermatocytogenesis, Spermatocyte, Spermatidogenesis, Spermatid, Spermiogenesis, Spermatozoon
seminal tract: Seminiferous tubules (Tubuli seminiferi recti, Rete testis, Efferent ducts) - Epididymis (Appendix) - Vas deferens - Ejaculatory duct Seminal colliculus
urinary tract: Internal urethral orifice - Urethra (Prostatic, Intermediate, Spongy) - Urethral crest - Urethral gland - External urethral orifice
Penis: Corpus cavernosum - Corpus spongiosum - Navicular fossa of male urethra - Glans penis - Fundiform ligament - Suspensory ligament - Foreskin - Frenulum
accessory glands: Seminal vesicles (Excretory duct of seminal gland) - Prostate (Prostatic utricle, Prostatic sinus) - Bulbourethral glands
