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It begins with a single fertilized egg and culminates 38 weeks later with the birth of a male child. It is a part of the stages of sexual differentiation. The development of the male reproductive system coincides with the urinary system. Their development can also be described together as the development of the urinary and reproductive organs.
Human fertilization is the union of an egg and sperm, occurring primarily in the ampulla of the fallopian tube. [1] The result of this union leads to the production of a fertilized egg called a zygote, initiating embryonic development. Scientists discovered the dynamics of human fertilization in the 19th century. [2]
Estrogens and progesterone promote mammary epithelial cell proliferation resulting in the formation of the primary and secondary ductal structure. Progesterone induces formation of tertiary side-branches in the mammary glands during puberty and during the luteal phase of the menstrual cycle upon which lobuloalveolar structures form under the ...
A gonad, sex gland, or reproductive gland [1] is a mixed gland and sex organ that produces the gametes and sex hormones of an organism. Female reproductive cells are egg cells, and male reproductive cells are sperm. [2] The male gonad, the testicle, produces sperm in the form of spermatozoa. The female gonad, the ovary, produces egg cells
Each ovary contains hundreds of egg cells or ova (singular ovum). Approximately every 28 days, the pituitary gland releases a hormone that stimulates some of the ova to develop and grow. One ovum is released and it passes through the fallopian tube into the uterus. Hormones produced by the ovaries prepare the uterus to receive the ovum.
Testosterone is the primary male sex hormone and androgen in males. [3] In humans, testosterone plays a key role in the development of male reproductive tissues such as testicles and prostate, as well as promoting secondary sexual characteristics such as increased muscle and bone mass, and the growth of body hair.
Likewise, male cephalopods have only a single testicle. In the female of most cephalopods the nidamental glands aid in development of the egg. The "penis" in most unshelled male cephalopods is a long and muscular end of the gonoduct used to transfer spermatophores to a modified arm called a hectocotylus. That in turn is used to transfer the ...
The immature ova originate from cells from the dorsal endoderm of the yolk sac. Once they have reached the gonadal ridge they are called oogonia. Development proceeds and the oogonia become fully surrounded by a layer of connective tissue cells (pre-granulosa cells). In this way, the rudiments of the ovarian follicles are formed.