The trophoblast is the outer layer of cells that make up the blastocyst. These cells provide nutrients to the developing embryo, and eventually develop into the placenta. During the later stages of cleavage, the trophoblast becomes distinguished from the inner layer of cells, which will develop into the embryo. There is a layer of fluid between the trophoblast and inner cell mass.

In a human egg cell the yolk—ooplasm—located at the cell center in an area containing the nucleus and nucleolus. The ooplasm is composed of fatty granules that support embryo development through the early stages of embryogenesis. In human oocytes, there is a relatively small amount of ooplasm compared to the embryos of other species.

During fertilization and throughout the process of cleavage, the developing embryo is located in the fallopian tube. Towards the end of cleavage, around day 5, the developing embryo enters the uterus, where it will implant in the uterine wall after blastulation.

During cleavage, gap junctions form between blastomeres, promoting cell-cell communication and coordinated development. 

Determinate cleavage is a process found in most protostomes, in which the developmental fate of cells is determined early on in the developmental process. In other words, blastomeres do not have the capacity to develop into any cell type.

Spermatogenesis is a continuous process starting at puberty. Sperm production takes place in the seminiferous tubules. There, each spermatogonium cell (2n) divides equally via mitosis to produce two identical primary spermatocytes (2n). Each primary spermatocyte undergoes meiosis I to produce two equally sized secondary spermatocytes (n). Each secondary spermatocyte then undergoes meiosis II to produce a total of four spermatids (n). The spermatids differentiate before moving to the epididymis.

Oogenesis, on the other hand, begins prior to birth and is a stop-start process. While still within the embryo, each oogonium (2n) produces two identical primary oocytes (2n) via mitosis; the primary oocytes remain dormant in small ovarian follicles until puberty. After the onset of puberty, hormones periodically stimulate the follicles to complete meiosis I and produce secondary oocytes (n). It is important to note, however, that meiosis I produces only one secondary oocyte—the other "daughter cell" is actually the first polar body, which is almost always rapidly degraded (though sometimes this polar body also undergoes meiosis II and produces a third polar body). This occurs because the primary oocyte divides unevenly, leaving the secondary oocyte with virtually all of the cytoplasm during cytokinesis. Secondary oocytes are released during ovulation, but they do not complete meiosis II until fertilization, when they are penetrated by a sperm. Meiosis II results in another polar body, again due to uneven division of cytoplasm during cytokinesis. 

The mature human ovum is formed through the developmental process known as oogenesis, which takes place during the first three months of fetal development. Ovarian follicles each contain one oogonium, which becomes a primary oocyte, then a secondary oocyte. No further division occurs until puberty.

Mitosis is a type of nuclear division in which one copy of each chromosome moves into each of two daughter nuclei to create identical daughter cells. Meiosis is also a type of cell division, in which a diploid cell divides twice to produce four haploid cells. Ovulation is the release of the secondary oocyte from the ovary, and fertilization is the union of a male sperm and female egg to produce a zygote. 

During spermatogenesis, spermatogonia become primary spermatocytes, then seconday spermatocytes. These divide to form two spermatids, which transform into functional spermatozoa. Through the process of meiosis, the chromosome number is reduced from the diploid number (46) to the haploid number (23).

Mitosis refers to the replication of somatic cells, creating identical daughter cells from a diploid parent. Migration occurs as the spermatogonia, spermatocytes, and spermatids move from the outermost edge of the seminiferous tube to the central cavity of the tuble. Proliferation is the repeated reproduction of new parts. Gametogenesis is defined as the development of gametes. 

During mitosis cells divide a single time and retain the exact same genetic material, producing two identical copies of the parent cell. During meiosis, cells divide twice and cross over during anaphase I. This produces a unique combination of chromosomes (recombinants) not seen in the parent cell.

Gametes are the haploid sex cells that are produced in the gonads (ovaries in females and testes in males). These are the primary sex organs.