Sexual dimorphism exists in many mammalian species where there are systematic differences between individuals of different sex that belong to the same genus. Systematic differences are observable in copulatory behaviors and neural circuits controlled by the brain. On the other hand, sexual determination is established by the presence or absence of an Sry gene. Sry on the Y chromosome leads to a cascade of events in which the fetus will form testes. Absence of the Sry gene triggers a female cascade of events where the female forms ovaries. Subsequently, gonadal steroids such as testosterone and estrogen drive sexual differentiation. Estrogen and testosterone are crucial for male typical behaviors where estrogen controls the masculine range of…show more content… In order to observe sex differences in the spinal cord, the consequences of spinal motor neurons are taken into consideration. Therefore, in order to see the effects flutamide is utilized in this lab. Flutamide is an androgen receptor blocker that does not affect any other hormonal and antihormonal activities (Caron, L. S., Bélanger, A., & Labrie, F., 1987). Flutamide is utilized in order to examine the effects that androgens have on spinal motor…show more content… SNB neurons are large neurons that reside in the lumbar region of the spinal cord ventral to the central canal. SNB neurons innervate sexually dimorphic muscles of the penis of the bulbocavernosus (BC) and the levator ani (LA). SNB neurons are more numerous in males than females (Grisham et al., 1992). Since flutamide had no effect in females SNB neurons (Grisham et al., 1992) the females who are treated with flutamide or control injections in utero should not be affected. As a result, the SNB neurons should remain constant across both groups of females. In contrast, flutamide was seen to reduce the number of SNB neurons in males therefore, males who are given control injections should have more SNB neurons than males who were treated with flutamide (Grisham et al., 1992) . As a result, there should be a main effect for treatment and an interaction between sex and treatment. In terms of SNB neuron sizes, flutamide “reduced the somal and nuclear area of SNB neurons” in males while having no effect in females (Grisham et al., 1992). Thus, SNB size should be lower for males treated with flutamide compared to males given control injections in utero. Consequently, females SNB size remains constant regardless of the
