Spermatogenesis and Spermiation - Anatomy & Physiology

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Introduction

Unlike the female production of gametes which occurs entirely before birth with gamete maturation occurring in a pulsatile fashion after puberty, male individuals produce gametes continuously from puberty onwards for the rest of their reproductive lives and the release of the gametes is constant. Spermatogenesis is the process of the gradual transformation of germ cells into spermatozoa. It occurs mainly within the seminiferous tubules of the testes and can be divided into three phases, each of which is associated with different germ cell types:

  • Proliferative phase - spermatogonia
  • Meiotic phase - spermatocytes
  • Differentiation phase / spermiogenesis - spermatids


Spermatogenesis Copyright Amy Cartmel 2008

The seminiferous tubule

Spermatogenesis Copyright Amy Cartmel 2008

The seminiferous tubules are the site of spermatogenesis. The 2 main cell types within the tubules which are involved in spermatogenesis are the germ cells, which will develop into sperm, and somatic cells known as Sertoli cells, which nuture the germ cells throughout the development process.

As the germ cells progress through their stages of development they move slowly from the basement membrane of the tubules through the tight junction of the Sertoli cells into the tubular lumen.

The proliferation phase

The spermatogonia go through several divisions

Hormonal Control of Spermatogenesis

The production of sperm is controlled by hormones influencing sertoli cells rather than sperm cells directly. Hormonal control is via the two gonadotrophins luteinising hormone (LH) and follicle-stimulating hormone (FSH).

  • LH acts on the interstitial leydig cells stimulating them to produce the androgen testosterone.
  • FSH acts on the sertoli cells within the seminipherous tubules stimulating production of Androgen Binding Protein as well as Inhibin



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