When cells are veryclose to one another, some of the mol-ecules on the cellsâ plasma membranesmay bind together in specific ways.Many of the important interactionsbetween cells in early developmentoccur by means of direct contact be-tween cell surfaces (figure 7.3 a).ecause these proteins may constituteless than 0.01% of the total mass of protein in a cell, puri-fying them is analogous to searching for a particular grainof sand in a sand dune! However, two recent techniqueshave enabled cell biologists to make rapid progress in thisarea. 7.1 Cells signal one another with chemicals.
The Maenads (pronounced Maynads) were female revelors in the cult of Dionysus. The god's frenzied Thracian worshippers, the Maenads, accompanied Dionysus on his travels crowned with wreaths of ivy, oak or fir and draped in the skins of animals.
Gonads. Gonads are the male and female primary reproductive organs. The male gonads are the testes and the female gonads are the ovaries. These reproductive system organs are necessary for sexual reproduction as they are responsible for the production of male and female gametes. Male Gonad Hormones. 2  Androgens are hormones that primarily influence the development of the male reproductive system. 3  Although found in much higher levels in men, androgens are also produced in women. 4  Testosterone is the main androgen secreted by the testes.