Human Reproductive System

The testis is the primary male reproductive organ responsible for the production of sperm and the hormone testosterone.

Seminiferous tubules are lined with germinal epithelium, which consists of spermatogonia (sperm-producing cells) and Sertoli cells.

The testes are a pair of ovoid glandular organs that are central to the function of the male reproductive system. The testes are responsible for the production of sperm cells and the male sex hormone, testosterone. The main male sex organs are the penis and the testicles, which produce semen and sperm.
Therefore, the correct answer is option D.

• Testes are the glandular glands that secrete hormone as well as produces male gametes. 
• It is located in the scrotal sac, outside the body, because the process of spermatogenesis (sperm or male gamete production) requires a lower temperature i.e., 2-3${^0}$C lower than the normal body temperature. 

The testes are a pair of ovoid glandular organs that are primary to the function of the male reproductive system. Its function is to produce sperm cells and the male sex hormone, testosterone.
So, the correct answer is option A.

In mammals, the process of spermatogenesis or the formation of sperm requires a lower temperature than the normal body temperature to produce viable sperms. Hence, the sperms are stored outside the body in a sac-like structure called scrotum.
So, if the testes do not move from abdominal cavity to the scrotal sac, the sperms will not be formed.
Thus, the correct answer is option D.

The semen, secreted by male contains 100-200 millions of sperms. The healthy sperms in the semen then go to the cervix, then pass through the uterus and then ultimately arrive at the ampulla part of the fallopian tube where they come to meet the ovum. Although so many sperms encircle the ovum, only one sperm is allowed to penetrate the ovum.
Thus, the correct answer is option A.

The testes are the male gonads in animals. The primary function of the testes is to produce sperms and to produce the testosterone hormone.
So, the correct answer is option A.

The process of spermatogenesis or the formation of sperms require a lower temperature (1-6 degree C lower) than the normal body temperature to produce viable sperms. Hence, the sperms are stored outside in a sac-like structure called scrotum.
So, the correct answer is option D.

• The testes are the male gonad in the animals, produces sperm and the testosterone hormone and so is the primary male reproductive organ. 
• Ovum is produced by the female reproductive organ, ovary, which is also responsible for the production of estrogen.

• The testis is the male gonad in animals. The primary function of the testes is to produce sperm (spermatogenesis) and to produce androgens, primarily testosterone.

• Each lobule of testes contains one to three seminiferous tubules in which the sperms are produced. 
• Each seminiferous tubule is lined on its inside by two types of cells called male germ cells (spermatogonia) and Sertoli cells. Sertoli cells are also known as nurse cells. 
• They provide nutrition to spermatozoa. Spermatozoa are developing sperms. It is formed during the last stage of spermatogenesis. This stage is known as spermiogenesis.
•  In this step, spermatids are transformed into spermatozoa (sperms) by the process of metamorphosis. Heads of spermatozoa are embedded in the Sertoli cells.

Human male germ cell is sperm. Each sperm is a single cell. During the last step of spermatogenesis, spermatids are transformed into spermatozoa by the process of metamorphosis. These spermatozoa are known as sperms. Mature sperm consists of a head, a neck, a middle piece and a tail. A plasma membrane envelops the whole body of sperm. The sperm head contains a very little cytoplasm, an elongated haploid nucleus, the anterior portion of which is covered by a cap-like structure, acrosome. Sperm fertilizes with ovum and leads to the formation of zygote.

The primary function of the testes is the production of male gametes, known as sperm, and the secretion of male sex hormones like testosterone. Ova are female gametes produced by the ovaries.