What effect shaving has on the development of comedones or acne is unclear.Some skin products might increase comedones by blocking pores, and greasy hair products (such as pomades) can worsen acne. Skin products that claim to not clog pores may be labeled noncomedogenic or nonacnegenic. Make-up and skin products that are oil-free and water-based may be less likely to cause acne. Whether dietary factors or sun exposure make comedones better, worse, or neither is unknown.A hair that does not emerge normally, an ingrown hair, can also block the pore and cause a bulge or lead to infection (causing inflammation and pus).Genes may play a role in the chances of developing acne. Comedones may be more common in some ethnic groups. People of Latino and recent African descent may experience more inflammation in comedones, more comedonal acne, and earlier onset of inflammation. Pathophysiology
Comedones are associated with the pilosebaceous unit, which includes a hair follicle and sebaceous gland. These units are mostly on the face, neck, upper chest, shoulders, and back. Excess keratin combined with sebum can plug the opening of the follicle. This small plug is called a microcomedo. Androgens increase sebum (oil) production. If sebum continues to build up behind the plug, it can enlarge and form a visible comedo.A comedone may be open to the air ("blackhead") or closed by skin ("whitehead"). Being open to the air causes oxidation, which turns it black. Cutibacterium acnes is the suspected infectious agent in acne. It can proliferate in sebum and cause inflamed pustules (pimples) characteristic of acne.
Cranioschisis (Greek: κρανιον kranion, "skull", and σχίσις schisis, "split"), or dysraphism, is a neural tube defect involving the skull. In this defect, the cranium fails to close completely (especially at the occipital region). Thus, the brain is exposed to the amnios and eventually degenerates, causing anencephaly.Craniorachischisis is on the extreme end of the dysraphism spectrum, wherein the entire length of the neural tube fails to close. See also
Rachischisis
Spina bifida


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