Development of the testis
Develops from:
– Coelomic epithelium: forms Sertoli cells.
– Primordial germ cells: form spermotogonia.
– Intermediate mesoderm: forms tunica albugenia, connective tissue stroma &
cells of Leydig.
Stages of development of Testis
** Indifferent stage: indifferent gonad is formed.
** Different stage: differentiation of gonad into testis or ovary.
SRY gene on Y chromosome is master gene for testis development.
– Primordial germ cells (endodermal) FIRST appear in wall of yolk sac close to
allantois in 4th wk.
– In 6th wk, these cells migrate along mesentery of hindgut & invade genital ridge
to induce differentiation of gonad into testis or ovary.
** They incorporate into primitive sex cords. That continue to proliferate &
penetrate into medulla to form testis cords.
– Toward hilum of gland, testis cords break up to form rete testis tubules.
** Later, a dense fibrous tissue capsule (tunica albuginea) derived from
mesoderm, separates testis cords from surface epithelium.
Develops from:
– Coelomic epithelium: forms Sertoli cells.
– Primordial germ cells: form spermotogonia.
– Intermediate mesoderm: forms tunica albugenia, connective tissue stroma &
cells of Leydig.
Stages of development of Testis
** Indifferent stage: indifferent gonad is formed.
** Different stage: differentiation of gonad into testis or ovary.
SRY gene on Y chromosome is master gene for testis development.
– Primordial germ cells (endodermal) FIRST appear in wall of yolk sac close to
allantois in 4th wk.
– In 6th wk, these cells migrate along mesentery of hindgut & invade genital ridge
to induce differentiation of gonad into testis or ovary.
** They incorporate into primitive sex cords. That continue to proliferate &
penetrate into medulla to form testis cords.
– Toward hilum of gland, testis cords break up to form rete testis tubules.
** Later, a dense fibrous tissue capsule (tunica albuginea) derived from
mesoderm, separates testis cords from surface epithelium.
