Read the given passage and answer the following questions:
Spermatogenesis results in the formation of sperms that are transported by the male sex accessory ducts. A normal human sperm is composed of a head, neck, a middle piece and tail. The process of formation of mature female gametes is called oogenesis. The reproductive cycle of female primates is called menstrual cycle. Menstrual cycle starts only after attaining sexual maturation (puberty). During ovulation only one ovum is released per menstrual cycle. The cyclical changes in the ovary and the uterus during menstrual cycle are induced by changes in the levels of pituitary and ovarian hormones. After coitus, sperms are transported to the ampulla, where the sperm fertilises the ovum leading to formation of a diploid zygote. The presence of X or Y chromosome in the sperm determines the sex of the embryo. The zygote undergoes repeated mitotic division to form a blastocyst, which is implanted in the uterus resulting in pregnancy. After nine months of pregnancy, the fully developed foetus is ready for delivery. The process of childbirth is called parturition which is induced by a complex neuroendocrine mechanism involving cortisol, estrogens and oxytocin. Mammary glands differentiate during pregnancy and secrete milk after child-birth. The new-born baby is fed milk by the mother (lactation) during the initial few months of growth.
Statement I: The spermatids are transformed into spermatozoa (sperms) by the process called spermiogenesis.
Statement II: LH acts on the Sertoli cells and stimulates the synthesis and secretion of androgens.
In the light of the above statements, choose the correct answer from the options given below.
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Statement I is correct but Statement II is incorrect.
Statement I: The spermatids are transformed into spermatozoa (sperms) by the process called spermiogenesis. — True. Meiosis in the testis gives four haploid spermatids. They are not yet sperms. They change shape and become sperms by spermiogenesis. The sperms are then released from the seminiferous tubules by spermiation.
Statement II: LH acts on the Sertoli cells and stimulates the synthesis and secretion of androgens. — False. At puberty, GnRH from the hypothalamus makes the anterior pituitary release LH and FSH. LH acts on the Leydig cells, which make androgens. FSH acts on the Sertoli cells, which release factors that help spermiogenesis. The statement gives LH the target of FSH.
NCERT Extract:
Gametogenesis – “… The spermatids are transformed into spermatozoa (sperms) by the process called spermiogenesis. After spermiogenesis, sperm heads become embedded in the Sertoli cells, and are finally released from the seminiferous tubules by the process called spermiation.”
Gametogenesis – “… The increased levels of GnRH then acts at the anterior pituitary gland and stimulates secretion of two gonadotropins – luteinising hormone (LH) and follicle stimulating hormone (FSH). LH acts at the Leydig cells and stimulates synthesis and secretion of androgens. Androgens, in turn, stimulate the process of spermatogenesis. FSH acts on the Sertoli cells and stimulates secretion of some factors which help in the process of spermiogenesis.”