An argon ion laser microbeam (488 and 514 rim) was used to selectively irradiate one of the to centriolar regions of rat kangaroo Potorous tridactylis (PtK2) prophase cells in vitro. The cells were sensitized to the laser radiation by treatment with acridine orange (0.1-0.2 /.tg/ml). Ultrastructural examination of the irradiated centriolar regions demonstrated that the primary site of damage was the pericentriolar material. This result suggests that nucleic acid is present in the pericentriolar material. Behavioral and ultrastructural analysis demonstrated that cells with one damaged pericentriolar zone could undergo (a) nuclear membrane breakdown, (b) chromosome condensation, (c) metaphase plate formation, and (d) cytokinesis. However, the chromosomes neither separated nor exhibited any anaphase movements. Detailed ultrastructural analysis revealed the presence of kinetochore microtubules on both sides of the chromosome mass and a lack of microtubules in the cytokinesis constriction. These results indicate that the pericentriolar material is important in spindle organization and essential for the formation of the interpolar microtubules.

Light and electron microscopy were used to study somatic cell reduction division occurring spontaneously in tetraploid populations of rat kangaroo Potorous tridactyl/s (PtK2) cells in vitro. Light microscopy coupled with time-lapse photography documented the pattern of reduction division which includes an anaphase-like movement of double chromatid chromosomes to opposite spindle poles followed by the organization of two separate metaphase plates and synchronous anaphase division to form four poles and four daughter nuclei. The resulting daughter cells were isolated and cloned, showing their viability, and karyotyped to determine their ploidy. Ultrastructural analysis of ceils undergoing reduction consistently revealed two duplexes of centrioles (one at each of two spindle poles) and two spindle poles in each cell that lacked centrioles but with microtubules terminating in a pericentriolar-like cloud of material. These results suggest that the centriole is not essential for spindle pole formation and division and implicate the cloud region as a necessary component of the spindle apparatus.

Intellectual disability (ID) with or without other anomalies is a common referral for genetic counseling. Sessions may include discussions of reproductive implications and other issues related to sex education. Patients with ID regularly meet barriers when trying to obtain sex education due to the misperceptions of others as being either asexual or that such education would promote inappropriate sexual behavior. In this pilot study, we surveyed genetic counselors to explore their experiences with being asked to provide sex education counseling and their comfort in doing so for patients with ID ages 9-17. Results were analyzed from 38 respondents. Caregivers and patients most frequently requested information on puberty, sex abuse prevention, and reproductive health. Genetic counselors were most comfortable when they could provide sex education counseling within the context of a particular condition or constellation of features. They were least comfortable when they lacked familiarity with the patient, caregiver, or the family's culture. The most frequently cited barriers that prevented genetic counselors from providing sex education counseling were lack of time, lack of training, the patient's ID being too profound, and a belief that genetic counselors should not be responsible for providing sex education counseling. While many respondents reported that providing sex education counseling is not considered within the scope of a genetic counselor's practice, they also noted that patients' families initiate discussions for which counselors should be prepared. Respondents indicated that resource guides specifically designed for use by genetic counselors would be beneficial to their practice. Genetic counselors have the opportunity to embrace the role of advocate and broach the issue of sexual health with caregivers and patients by directing them toward educational resources, if not providing sex education directly to effectively serve the needs of patients and caregivers.

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Clinicians need to provide accurate, up-to-date, and balanced information to parents following a prenatal or postnatal diagnosis of Down syndrome and other genetic conditions. Families want information about the genomic outcomes and medical issues, but they also want information about life outcomes and social supports. Because the anticipated outcomes of a condition can change significantly based on available social support, health care, and services, it is important for clinicians to stay up-to-date about new developments and credible, medically reviewed information about Down syndrome and other genetic conditions to access resources for clinical care.