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The ZW sex-determination system is a chromosomal system that determines the sex of offspring in birds, some fish and crustaceans such as the giant river prawn, some insects (including butterflies and moths), the schistosome family of flatworms, and some reptiles, e.g. majority of snakes, lacertid lizards and monitors, including Komodo dragons.
Zamia species often produce more than one cone close to the tip of the stem or at the terminal of the caudex where it intersects with the cones, also called strobilus, of Z. integrifolia are dioecious. The male strobilus and the female strobilus are found on two separate plants. The cones on the female plant are thick and have red-orange seeds.
The underside of the male's hindwing lacks the enclosed yellow basal spot. [4] While the female Zabulon skipper has one form, the female Hobomok skipper has two; the normal form and the pocahontas form. The upperside of the pocahontas form has smaller glassy spots and has one glassy spot near the forewing costa. [3]
Such an adaptation would be "exceptionally difficult" because of the need for male and female genital structures to change at the same time. [ 4 ] Female penetration of males is known in a few species, such as seahorse , but only Neotrogla females have a well-defined organ that can be described as a penis. [ 3 ]
Epididymal cysts is a mass that forms in the epididymis. [10] These cysts differ from spermatoceles as they contain clear fluid, rather than seminal fluid. In addition, spermatoceles are more likely to be found on the head of the epididymis. [19] Other abnormalities can be detected during male genital examination including Peyronie's disease.
Two use homomorphic male heterogamety, one uses XX/XY, one uses ZZ/ZW. Remarkably, the X and Z chromosomes are homologous, and the Y and W as well. Dmrt1 is on autosome 1 and not sex-linked. This means that an XX female individual is genetically similar to a ZZ male individual, and an XY male individual is to a ZW female individual.
In mathematics, the genus is a classification of quadratic forms and lattices over the ring of integers. An integral quadratic form is a quadratic form on Z n, or equivalently a free Z-module of finite rank. Two such forms are in the same genus if they are equivalent over the local rings Z p for each prime p and also equivalent over R.
The small cluster of cells injected by the male cypris differentiates into a loosely connected mass of sperm-producing germ cells, once it reaches its destination inside the female. Being nothing more than sperm-forming cells, these adult male rhizocephalans represent the simplest form of male in the entire animal kingdom.